After 60 years, the mysterious origin of the quasar is finally revealed

Quasars are among the brightest objects in the universe and they could be much brighter than a trillion stars thrown together! But how it arose has been shrouded in mystery for decades. However, new research changes that.

You can read about it in the magazine Monthly Notices of the Royal Astronomical Society. Quasars “ignite” when galaxies collide, British researchers wrote in the journal. This means that our Milky Way, which is doomed to collide with the Andromeda Galaxy, will also eventually contain a quasar.

About quasars
The first quasar was discovered about 60 years ago, and it immediately stood out due to its extreme brightness. Quasars can be counted among the brightest objects in the universe. But what exactly are these things? In fact, a quasar is nothing more than a very bright center of active galaxies. The very bright glow from this center is due to the presence of a supermassive black hole surrounded by an accretion disk of gas and dust. Gas falling from this accretion disk towards the black hole releases huge amounts of energy (in the form of light and radiation). As a result, the object can be observed at very great distances. In fact, quasars are bright objects powered by massive supermassive black holes that expel large amounts of energy while swallowing any gas, dust, or other matter that comes too close.

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Although researchers were able to explain why quasars are so bright, it remained unclear what caused the galactic center to become so bright, or how exactly such a quasar ignites. To change that, the scientists observed 48 galaxies with quasars and compared them to more than 100 galaxies without quasars. The research reveals that galaxies containing quasars were more likely to interact or collide with other galaxies. It strongly suggests that quasars result from collisions between galaxies, the researchers wrote.

collision force
How, exactly, does this work? First of all, imagine that most galaxies naturally contain the components of a quasar, ie: a supermassive black hole and large amounts of gas. But this gas is usually at a great distance from the galactic core – where this supermassive black hole resides. As a result, it remains out of reach of the black hole and does not collect in the accretion disk from where it is pulled towards the black hole, while releasing large amounts of energy. Therefore, a quasar does not form. However, it becomes different when such a galaxy collides with another. In such a scenario, gas from the outer regions of the galaxy moves toward the center of the galaxy, where it falls prey to the black hole and generates massive amounts of energy: a quasar is born.

star formation
The formation of such a quasar has far-reaching consequences for the galaxy. That galaxy is losing massive amounts of gas. And since it needs gas to form stars, it may be unable or barely able to give birth to new stars for billions of years in a row.

It is a scenario that does not occur in many galaxies many light years away from our own. No, something similar awaits our Milky Way, researcher Clive Tadhunter assures. “Quarantines are some of the most extreme phenomena in the universe, and what we saw probably represents the future of our galaxy when it collides with the Andromeda Galaxy in about five billion years. It’s exciting to watch events like this and finally understand why they happen.”